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I completed an installation into a gp9, cab no 8550.  Locomotive responds to cab 1 but only proceeds down track for about 10 feet.  It still responds to direction input (lights change direction) but does not respond to the throttle input once it has stoped. Location on the layout is inconsistent.  The only way to regain full control is to cycle track power on and off.  Any thoughts on what to troubleshoot?

Last edited by necrails
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An update.  Pulled the shell, checked all the connections and stretched the antenna out, reseated the board.  Locomotive still responds sporadically with a new twist.  The pullmor motor will crawl so I let it creep around the layout to see if the signal loss was time dependent.  It seems at low speed there is no signal loss BUT if the throttle is advanced to what seems to be over 30 smph the locomotive stops.  If the direction is changed it will proceed several feet then stop.  At that point a flick of the power is required to bring it back to life. 

I do not have a spare r4lc.  Can I pull one from a non AC commander to test further?  Based on symptoms is this a course of action?

Did you properly install the caps on the motor?  Bypassing the brushes is key to maintaining the signal.  Truthfully, that or some continuity of the power seem like the top suspects here.  The fact that it's stopping and will immediately start moving again suggests that.

One thing of note.  There have been some issues with the R4LC with failures that look just like this, I have several that came back to me in customer jobs that exhibited the same kind of issue.

Appreciate the responses, I will check the caps and wiring to the motor as well as repeating the seating of the board.  No there is no sound connected to this, I was looking only for the ability to operate the locomotive with the rest of the TMCC fleet.  Given the age and simplicity of the unit I did not think any further investment was warranted.

I only mention because integration of sound can cause issues with corruption of the serial data and or the R4LC processor operation.  Rare and usually when composite parts used.  I have seen the very timed based failure.  Interesting that John has seen this with some R4LC ERR boards too.  Seems similar.  G

An update for the ongoing mystery.  Checked all the connections to the AC commander especially the antenna, ran the loco conventional with no problem at all.  Then ran it under TMCC, ran fine for 15 minutes.  Figured problem solved.  Added front and rear led lights, attempted to run this with TMCC and problem returned.  I doubt the lights have anything to do with the issue but will remove them and try again.  Still have to find a R4LC or R2LC to swap into this critter.  Since I generally do not like football this will be a New Years Day experiment.  Happy New Year to all.

Final update I hope.  Problem ac commander had a r2lc c08 silver board.  I pulled it and placed on what I had, a r4lc s08 s01 board.  Locomotive works like a charm.  For fun I placed the r2lc in the donor locomotive.  Low and behold it too worked like a charm.  Returning it to the original problem loco and problem returned.  Right now my go to solution is to make the swap permenant.  I am not one to quibble about outcomes but why would the simple swap work?

Last edited by necrails

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